<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    var queue={
        name:'abc',
        age:19,
        vm:{
            _watcher:{}
        },
    }
    queue.vm._watcher=queue;
    var watcher = queue;
    var vm = watcher.vm; //获取到虚拟dom
    if (vm._watcher === watcher) { //判断watcher与vm._watcher 相等
          alert(1)
    }

</script>
</body>
</html>